Study Guide (lecture # 8)
Book pages: 233-238, 108 (figs. 4.9 & 4.10), 178 (fig. 5.8)
Review:
(lecture # 7)
- moisture variables
- momentum budgeting (in latitude circles)
- partitioning variables (Appendix A)
Today's topics:
- maintenance against friction (chapter: 6.2.2)
Jargon:
linear momentum, horizontal tilts, mid-ocean
troughs, subtropical high, Siberian High
+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
Maintaining momentum against friction:
(Section 6.2.2)
- crude calculation procedure has:
- geostrophic winds except in boundary layer
- cannot get balance between friction loss and ageostrophic transport
- geostrophic winds transp momentum if have horizontal tilts
- maintaining westerlies against friction requires tilted eddies
- Shape as a proxy for momentum flux (p. 108)
- example shapes
- examples from a weather map in spherical geometry
- horiz tilts seen even in low latitudes (when streamfunction, "psi" field plotted)
-in midlats: troughs near E coasts (N. Hemis)
- in subtropics & tropics: mid-ocean troughs (both hemis)
+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
Some unanswered questions:
- what roles do the meridional cells play?
- why is subtropical jet between the Hadley and Ferrel cells
if eddies maintain momentum?
- how are the meridional cells and the eddies working together?
- what does the transport look like in the vertical?
- can we explain the maintenance of the jets?
- are there other important issues in the momentum budget?